The wireless industry is experiencing increasing growth in data and service traffic. Smart phones and data devices are demanding more and more from wireless networks. To off-load the traffic in densely populated areas and increase indoor coverage, small cells (e.g., pico cells) have become a feasible solution. Namely, heterogeneous networks (HetNets) are now being developed, where cells of smaller footprint size are embedded within the coverage area of larger macro cells or at least partially overlapped by the larger macro cells, primarily to provide increased capacity in targeted areas of data traffic concentration. Such heterogeneous networks try to exploit the spatial variations in user (and traffic) distribution to efficiently increase the overall capacity of the wireless network. Those smaller-sized cells are typically referred to as small cells in contrast to the larger and more conventional macro cells.
In Long Term Evolution (LTE), the handover (HO) is optimized for a UE moving from one macro cell to another macro cell.
The existing LTE HO is mainly based on an Event A3 in the 3GPP TS 36.331 standard, the entire contents of which are herein incorporated by reference. Received signal strength (RSRP) is used as a metric for an eNodeB (enhanced NodeB) to make HO decisions. The HO parameters in the current macro cellular network are intended for the macro-to-macro HO. The macro cells have many of the same parameters such as transmit power and coverage area.
For example, for a macro-macro HO, a late HO initiation is used to reduce a ping-pong effect or a number of unnecessary HOs.